The present invention relates to a semiconductor device having two or more bonding option pads.
Typical semiconductor devices such as dynamic read-only memories (DRAMs) have a semiconductor chip provided with a bonding option pad. The bonding option pad is for use in "choosing" functions of a semiconductor device during a bonding step. A reason for the necessity of such a bonding option pad is that a function of the semiconductor device should be modified depending on functions or requirements of instruments wherein the semiconductor device is mounted. For example, the semiconductor device can be used as a dynamic RAM for a single bit (.times.1 bit) configuration by means of connecting the bonding option pad to one of a lead on the power supply side (hereinafter, referred to as a lead on the higher potential side) and a lead on the ground lead (hereinafter, referred to as a lead on the lower potential side). On the other hand, the semiconductor device can be used as a dynamic RAM for a four bits (.times.4 bit) configuration by means of connecting the bonding option pad to the other lead.
Selective connection between the bonding option pad and the lead on the higher or the lower potential side allows to provide semiconductor devices having various functions.
A conventional semiconductor device of this type is disclosed in, for example, Japanese Patent Laid-open No. 62465/1993 (Tokkai Hei 5-62465)(hereinafter, referred to as a cited reference). The semiconductor device disclosed comprises the leads on the higher and the lower potential sides extended in a predetermined direction with the bonding option pad positioned between the leads on the higher and the lower potential sides adjacent thereto. The bonding option pad is bonded to either the lead on the higher potential side or the lead on the lower potential side. In this semiconductor device, the potential on the bonding option pad corresponds to the one applied to the leads on the higher or the lower potential side. This configuration allows avoiding a level fluctuation at an input of a selective signal generation circuit connected to the bonding option pad.
The cited reference discloses only the case where the leads on the higher and the lower potential sides are positioned on both sides of the single bonding option pad. It is not contemplated therein to provide two or more bonding option pads.
There is a conventional semiconductor device having two or more bonding pads, an example of which is described now. The bonding pads are arranged in one direction on a semiconductor chip. The bonding option pads are each connected to the leads on the higher and the lower potential sides at the ends of the pad. The leads are in parallel with each other and configured into a bus. The leads on the higher and the lower potential sides are thus extending in the direction parallel to the bonding option pads.
In the semiconductor device of the type described, it is difficult to arrange an additional signal lead due to the leads on the higher and the lower potential sides because they are in parallel with the bonding pads. Therefore, the signal lead and a signal pad allocated thereto are connected to each other by means of, for example, over-bonding with a bonding wire crossing across the lead on the higher potential side.
Connection between the signal pad and the signal lead by the over-bonding requires to ensure complete insulation of the bonding wire in order to avoid electrical contact between the bonding wire for the over-bonding and the lead on the higher or the lower potential side. To this end, the bonding wire for the over-bonding is away from the lead on the higher or the lower potential side at a sufficient distance. In addition, the bonding wire itself is coated with an insulating material.
Furthermore, the semiconductor chip is enlarged because of a resin used to seal it because a larger amount of resin is used to increase the thickness of the resin after sealing.
Accordingly, an object of the present invention is to provide a semiconductor device in which a lead on the higher or the lower potential side connected to a bonding option pad has no adverse effect on other leads.
Another object of the present invention is to provide a semiconductor device in which the connection between a signal pad and a signal lead is achieved without over-bonding.
It is yet another object of the present invention to provide a semiconductor device of which manufacturing requires no consideration about electrical insulation of a bonding wire to be used for the bonding option pad.